Alcoholic fragrances, a group of plant fragrance ingredients, such as geraniol, linalool, benzyl alcohol, (Z)-3-hexenol, 2-phenylethanol, and C13-norterpenoid alcohols, have an important role in fragrance emission from flowers, tea, fruits, wine, and others. Among these fragrance ingredients, geraniol, linalool, and others, which are considered to play an important role in fragrance emission from flowers, have been known to be present as fragrance precursors in the form of disaccharide glycosides such as β-primeveroside (6-O-β-D-Xylopyranosyl-β-D-glucopyranoside) or the analogues thereof. In addition to these fragrances, some of colorants and physiologically active substances such as medicinal components are known to be present in the form of disaccharide glycoside or its analogue.
Enzymes having an action to cleave the disaccharide unit by acting on these fragrance components or disaccharide glycosides of physiologically active substance precursors have been isolated, for example, form tea leaves (see Patent Document 1). Although industrial application of these enzymes is attracting attention, the supply sources are limited, and thus, there was a strong need for development of a method of producing such an enzyme industrially and cost-effectively in a greater amount. On the other hand, it is also known that such a precursor disaccharide glycoside or the analogue is resistant to liberation of its aglycone with conventionally available β-glucosidases.
Under the circumstance above, the applicant had proposed a microorganism-derived diglycosidase that is readily produced from unlimited sources and has an enzyme activity to act on such a disaccharide glycoside, releasing its disaccharide sugar and aglycone (see Patent Document 2).    Patent Document 1: Japanese Unexamined Patent Publication No. 8-140675    Patent Document 2: WO 00/18931
However, the diglycosidase produced by Aspergillus fumigatus described in Patent Document 2 had a problem in safety, because Aspergillus fumigatus may possibly cause opportunistic infection. In addition, the enzyme was still unsatisfactory in enzyme activity and also in thermal stability, as it is inactivated at 55° C.
An object of the present invention is to provide a novel diglycosidase higher in safety, enzyme activity, and heat resistance than conventional diglycosidases, and a gene coding the same.